This proposal requests the renewal of our major source of long-standing funding for investigating transcription, chromatin, and epigenetics in pathophysiological mechanisms underlying pancreatic diseases. Our studies will directly extend our knowledge on common diseases, such as chronic pancreatitis and pancreatic ductal adenocarcinoma (PDAC), both painful and incurable disorders of the exocrine pancreas for which effective prevention protocols and treatments remain to be fully developed. Our OVERALL OBJECTIVE is to investigate how epigenomic regulators work as nuclear effectors of common mutations associated with human pancreatic diseases. Although we believe that our concepts and methodologies can be applied to any ?mutation-epigenetic-disease triad?, we will focus on understanding histone-based pathways as effectors of KRAS in established genetically-engineered mouse and human patient-derived models of pancreatic diseases. Notably, while similar to genetic alterations epigenetic changes are inheritable, they can be reversible by pharmacological treatment. Our PRELIMINARY DATA report the discovery of a key role for the Histone H3 Lysine 9 (H3K9) methylation pathway and its associated methyltransferase, EHMT2, as an epigenetic regulator of oncogenic KRAS. EHMT2 together with its paralog EHMT1 are the main histone lysine methyltransferases responsible for catalyzing histone H3K9 dimethylation. However, no information is known regarding the function of EHMT1 and EHMT2, either separately or as a complex, in relationship to pancreas physiology or pancreatic diseases. We will test a combined, mechanistic and translational CENTRAL HYPOTHESIS, namely that the EHMT1/EHMT2 complex works as an epigenetic effector of KRAS during ADM and PanIN formation as well as their progression by pancreatitis. Our SPECIFIC AIMS are: 1. To determine mechanisms by which inactivation of the EHMT1/2 complex antagonizes KRASG12D-mediated ADM and PanIN formation alone and in pancreatitis; 2. To evaluate biochemical mechanisms by which KRAS signaling in pancreatic cells regulates the enzymatic activity of the EHMT1/2 complex; and 3. To discover epigenetic mechanisms by which the EHMT1/2 complex mediates the effects of KRAS. We will use an extensive battery of cellular, molecular and whole organism experiments, executed in a highly collaborative environment with state-of-the-art techniques. By focusing on better understanding epigenomic pathways that serve as effectors downstream of common mutations in the pancreas, our design seeks to maximize the yield of rapidly translatable mechanistic knowledge. Discoveries from this proposal will have a valuable positive impact because the application of concepts, techniques, and drugs from the field of epigenomics is anticipated to provide new opportunities for the management of patients affected by pancreatic diseases, thereby bearing significant biomedical relevance.